1. Field of the Invention
The present invention relates to a system for generating an oil mist for lubricating the internal parts of a handheld type four-cycle engine which is used mainly as a power source for portable working apparatus such as a trimmer. In particular, it relates to an improvement of a system in which an oil slinger rotated by a crankshaft is provided inside an oil tank provided on one side of an engine main body, and an oil mist is generated by scattering the oil stored inside the oil tank by rotation of the oil slinger.
2. Description of the Related Art
An oil mist generation system which is already known, for example, in Japanese Patent Application Laid-open No. 11-326012, which discloses a single oil slinger having a plurality of vanes, the forward end of the vanes being bent, is fixed to the crankshaft of an engine so that the oil stored in the oil tank can always be scattered by rotation of the above-mentioned vanes regardless of the operational position of the engine.
However, since only one oil slinger is rotated in the above-mentioned conventional system, a peripheral wall of the oil tank housing the oil slinger is inevitably limited to a circular shape, the degrees of freedom in choosing the shape of the oil tank is extremely low and the layout of the equipment adjoining the oil tank is highly restricted.
The present invention has been carried out in view of the above-mentioned circumstances. It is an object of the present invention to provide an oil mist generation system for use in the above-mentioned handheld type four-cycle engines. The system allows the shape of the peripheral wall of the oil tank to be in various shapes besides a circular shape.
In accordance with a first aspect of the present invention in order to achieve the above-mentioned object, there is proposed an oil mist generation system in a handheld type four-cycle engine including an oil slinger which is provided in an oil tank disposed on one side of an engine main body and which is rotated by a crankshaft, the oil slinger scattering oil stored in the oil tank by the rotation by of the oil slinger so as to generate an oil mist, wherein the oil mist generation system includes a drive gear provided on the crankshaft, and at least three oil slingers supported on three support shafts and simultaneously driven by the drive gear, the three support shafts being arranged around the drive gear.
In accordance with the above-mentioned first aspect, it is possible to freely change the shape of the peripheral wall of the oil tank surrounding the oil slingers by selecting the positions around the drive gear of the three support shafts supporting each of the oil slingers, and the degrees of freedom in the layout of the equipment adjoining the oil tank thus increase.
In accordance with a second aspect of the present invention, in addition to the above-mentioned characteristic, there is proposed an oil mist generation system in a handheld type four-cycle engine wherein a rotating member of a valve operation mechanism functions as part of the oil slingers.
The above-mentioned rotating member corresponds to the cam gears 36, 136 and 137 in the embodiments of the present invention below.
In accordance with the above-mentioned second aspect, since the rotating member of the valve operation mechanism functions as part of the oil slingers, the number of special oil slingers can be reduced and the structure of the oil mist generation system can thus be simplified.
The above-mentioned object, other objects, characteristics and advantages of the present invention will become apparent from an explanation of preferable embodiments which will be described in detail below by reference to the attached drawings.